You can upload an SSH private key into a project via the TeamCity web interface.

Supported Key Format

TeamCity supports keys in the OpenSSH format only. If your private key uses a different format, it has to be converted to the OpenSSH.

For example, the Putty private key format (*.ppk) not supported by TeamCity can be converted to the OpenSSH format using PuTTY Key Generator: use the menu Conversions -> Export OpenSSH key.

Uploading SSH Key to TeamCity Server

Go to the Administration | <ProjectName> page.

On the left of the page, in Project Settings, click SSH Keys.

On the page that opens, click Upload SSH Key.

In the dialog that opens, select a private key usually stored in <USER_HOME>/.ssh/id_rsa or <USER_HOME>/.ssh/id_dsa.

When you upload an SSH key for the project, it is stored in <TeamCity Data Directory>/config/projects/<project>/pluginData/ssh_keys. TeamCity tracks this folder and is able to pick up new keys on the fly. The key will be available in the current project and its subprojects.

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The access to the TeamCity Data Directory must be kept secure, as the keys are stored in an unmodified/unencrypted form on the file system.

Once the key is uploaded, a VCS root can be configured to use this uploaded key.

SSH Key Usage

The uploaded and referenced in a VCS root SSH key is used on the server and is also passed to the agent in case agent-side checkout is configured.

During the build with agent-side checkout, the Git plugin downloads the key from the server to the agent. It temporarily saves the key on the agent's file system and removes it after git fetch/clone is completed.

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The key is removed for security reasons: e.g. the tests executed by the build can leave some malicious code that will access the build agent file system and acquire the key. However, tests cannot get the key directly since it is removed by the time they are running. It makes it harder but not impossible to steal the key. Therefore, the agent must also be secure.